#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define pi pair<int, int>
#define F first
#define S second
#define pb push_back
#define mp make_pair
#define PI acos(-1.0)
#define N 1000000
using namespace std;
ll t,n ,m , a, b;
bool vis[200200], ans;
vector<vector<int>> G;

bool DFS(int u){
    vis[u] = true;

    int cnt = 0;
    for (auto i : G[u])
        if (vis[i]) cnt++;
        else return DFS(i);

    if (cnt > 1) return false;
    return true;
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    cin >> t;
    while(t--){
        cin >> n >> m;
        G.resize(n+1);
        G.clear();
        for (int i=0; i<m; i++){
            cin >> a >> b;
            G[a].pb(b);
            G[b].pb(a);
        }
        memset(vis, false, sizeof vis);
        ans = DFS(1);
        cout << (ans ? "Yes" : "No") << '\n';
    }

    return 0;
}